To this day, energy conservation, emission reduction, and environmental protection continue to be goals pursued by humanity. Passive radiation cooling, as a zero-consumption refrigeration technology, offers substantial opportunities for reducing global energy consumption and carbon dioxide emissions. It is of great significance to develop high-performance passive radiation cooling materials from sustainable materials. In this work, polyvinyl alcohol (PVA) and nanocellulose fibers (CNFs) were used as raw materials to build a hydrophobic aerogel with high strength, satisfied heat insulation and qualified radiative cooling effect by freeze-casting. The obtained aerogel with borax/CNFs = 2: 5 by directional freezing processed excellent mechanical property (compressive strength = 291 KPa) under low density of 38.1 mg·cm